(1) Field of the Invention
This invention relates to an illumination device, and more particularly relates to an illumination device adapted to a projecting apparatus.
(2) Description of the Related Art
FIG. 1 is a block diagram of a typical projecting apparatus 10. As it shows, the projecting apparatus 10 has an illuminating device 12, an image module 14 and a projection module 16. The illuminating device 12 is utilized for providing high brightness light beams for the projecting apparatus 10. The image module 14 converts the light beams from the illuminating device 12 into image beams corresponding to the image signals from outward. The projection module 16 projects the image beams to a screen.
FIG. 2 is a schematic view of the typical illuminating device 12 of the projecting apparatus 10. As it shows, the illuminating device 12 includes a lamp 122, a power drive module 124, and a fan 126. The lamp 122 is utilized to provide high brightness illumination for the projecting apparatus 10. The power drive module 124 has an igniting module 124a and a power module 124b. The power module 124b transforms the inputted voltage signal Vin into a low voltage signal V1 (about 380V) for the igniting module 124a. During ignition, the igniting module 124a transforms the low voltage signal V1 into a high voltage signal V2 to drive the lamp 122. The fan 126 is disposed at a side of the lamp 122 to generate airflow (shown by the arrows) for cooling the lamp 122.
The power drive module 124 outputs the high voltage signal V2 to drive the lamp 122. The high voltage signal V2 may reach as high as 5000V when ignition. Thus, a high voltage power line 123 is needed to connect the lamp 122 and the power drive module 124, instead of a general low voltage power line. In addition, to avoid heat generated by the lamp 122 affecting normal operation of the power drive module 124, the power drive module 124 is kept away from the lamp 122. Thus, a long high voltage power line 123 is used to connect the lamp 122 and the power driven module 124.
The cost of the high voltage power line 123 is higher than the cost of the low voltage power line. The usage of the long high voltage power line 123 increases the cost of the whole device. Additionally, the high voltage signal V2 transmitted on the high voltage power line 123 disturbs neighboring electrical equipments, which may further reduce reliability of the electrical equipments. Taking FIG. 2 for example, since the power drive module 124 is connected to the lamp 122 by the high voltage power line 123 detouring the fan 126, the operational reliability of the fan 126 is affected by the high voltage signal V2 on the high voltage power line 123.